You know it was coming back to get you: smoke on roof edges.

No. This was already discussed earlier. Geometrically, the roof surface is a section of a two-dimensional plane. It doesn't have a side edge. Either you're below it and can see the surface from below (unless blocked by the wall), or you're above it and can see the surface from above.

If you're exactly on the same plane, but beside it, there are arguments to be made both ways. But if you're below it, you can't see its upper surface, only its lower surface.

 

And just to add to QueensGambit's point; a physical object will likely have a rounded lip that has a tangent that's not aligned to the horizon that may come from wear-and-tear, glue line, or whatever*. That surface is arguably not part of the roof's upper surface as it is of a geometric shape that can't support a trooper.

* which, let's just say, is a bit of a microscopic geometric hell-scape to resolve the volume of a template of

 

The rules don't refer to whether you can throw smoke on either a "roof" or a "surface," so whether the word "roof" refers to only its surface or also its edge (i.e. the top part of the wall) is irrelevant. The rules say you can throw the smoke at a "point on the table." The rest is us trying to figure it out.

However, assuming you have to throw the smoke onto a horizontal surface that you can see - which I think we all agree is correct - then "basic math," as you put it, tells us that you can't see the surface of the roof from below. That's not some sort of change to how the game is played. It's always been that way, although not universally accepted, it's pretty obvious from the way surfaces work.

 

*sigh*. You just argued that you can see "a point on a surface" without being able to see "the surface." If you can't see the surface then you can't see any points on it.

If you're above the surface, then you can see down onto it. You can see an infinite number of points on it, and can choose one of them to target your smoke.

If you're below the surface, you can't see any point on the top side of the surface. I don't see how that could be any more obvious. If you try to throw smoke up, you'll hit either the wall, or the bottom side of the surface.

It's clear from your diagram. If you consider your point A(1,2) to be part of the red surface (which, mathematically, is debatable), then the LoF you've drawn hits that red surface from its underside.

Anyway, I'm done with this one. The idea that you can throw smoke up in this way is convoluted and mathematically false, but you're right that it's not going to go away entirely unless CB rules on it. So if your point is that a ruling would be nice, we can agree on that!

 

Just a small reminder; nothing in Targetless say you're allowed to ignore this bullet point from line of fire: "The Trooper must be able to see part of the volume of its target, with a minimum size of 3x3mm."

 

I'm completely with you there. Mathematically the very edge of the roof (A) is part of both the vertical (wall) and horizontal (roof) plane.
RAW this is correct.

But as things have been going RAW is frequently irrelevant if it wasn't what the rule was designed for.
That design is invisible to us and we basically have to sit here in the dark and wait for a clarification on anything that's not crystal clear.
Simply because of precedence for rulings and FAQs not giving a single fuck about the RAW if it's now in line with the rule writer's intent, which again, can be completely unrelated to RAW (see Stealth FAQ preventing targeting, while Stealth itself only affects ARO generation).

This one was ruled in N3, which means it's now obsolete.
So for now there's no clean answer unless IJW nailed the question with an answer the last time it came up a few weeks ago.

We do know the intent of the rule here though.
The intent is you have to use Spec Fire to get a Smoke on a roof.
And you can't chugg a Smoke on a wall.
All because of the very unclear phrase of "on the table" the autor didn't bother to specify further.

edit:
The 3x3 rule would be nice and clean if we could apply it nice and simple to a surface on the game table
"Line of Fire (LoF) is the criterion by which players determine whether a Trooper can see its target. The Line of Fire (LoF) is an imaginary straight line that joins any point of the volume of a Model, Token, Marker or valid target to any point of the volume of another."

• The Trooper must be able to see part of the volume of its target, with a minimum size of 3x3mm.
• LoF can be drawn from any point of the Trooper's Silhouette to any point of the target's Silhouette without being obstructed by any pieces of scenery or Models (friendly or enemy).

This doesn't provide final clarity within the existing rules on how to play it.
Volume is an attribute for 3dimensional objects which the table or a roof without the attached building can't satisfy.
So you would technically be fine to target the edge from below as long as you can see the wall (which is necessary to give the target a 3d volume/"Silhouete").

Honestly man, if you don't get what he's saying and why he is correct AFTER he gave you the geometrical proof I don't know if you should try to correct people about math.
A is part of both planes and visible in a 270° angle for obvious reasons. Read up on what makes a point of intersection a point of intersection, it's basically in the name, the visual and the definition. Kinda hard to miss.

 

Yes, point A is visible, but as I said, if A is part of the surface of the building, then it's visible only from the bottom side of the surface, not the top side.

If you can throw smoke at A, then you can also throw smoke at the underside of an overhang. It's a horizontal surface after all. That's not the case, because when we talk about horizontal surfaces in Infinity, we're obviously talking about their top sides, not their undersides.

As for whether A is in fact part of the roof: a given point can be inside, outside, or on the boundary of a polygon. Being on the boundary of a polygon is not the same thing as being inside it (https://en.wikipedia.org/wiki/Point_in_polygon). So yes, it is in fact mathematically debatable whether A is even part of the roof at all.

 

No. A is visible 270° from roof and ground level. Your thinking is incorrect.

My main argument here is that the rules don't give a clear answer, didn't consider the mathematical implications and don't work strictly RAW.
Which your example of horizontal surfaces from below just backs up.
The rules pretty much forget to aknowledge ceilings exist.
The only thing that rules out walking under a bridge is yet again the "on the table" piece in the rules. Which remains insufficiently clear to interpret a lot into it (but is the only thing we have available).

We agree that you CAN'T chugg a Smoke without LOF on a roof.
No idea why you want to die on a hill claiming you understand quite simple math better than everyone else. Seriously you have a nice and accurate drawing with colours and everything, what's the point of picking a hill that ridiculous to die on when it doesn't even change the outcome?

 

If by "everyone else" you mean you and Sirk. All the other posters in the thread agree that you can't see the roof from below. The geometry is obvious, and has been explained over and over in detail.

 

Can we go back to discussing whether an Impact Template Weapon (fired from above) targeting a point on the edge of a roof can hit targets below the plane of the roof?

That's much more interesting, because you don't need to see a 3mm x 3mm area so Sirk's argument becomes relevant.

[emoji14]

 

Also works for Spec Firing on the Edge of a Roof.
We can all agree that's possible.

A point belonging to the edge has no depth into either the wall or roof.

Assuming perfectly cube shaped terrain any point on the roof edge has completely unobstructed LOF to anything protruding from the wall/roof, touching the wall/roof, leaning onto the wall/roof, walking onto the wall/roof etc.

Any point on the edge can see 3/4 of the volume of a Circular Impact sphere originating from that corner.
The corners of the roof can see 7/8th of the volume of a Circular Impact sphere originating in that corner.

 

Yeah, that's an interesting one. I think it has to be Spec Fire (otherwise the template has to be centered on the target Trooper, so can't be centered right at the edge).

I predict that @ijw 's answer would be: he doesn't like playing with perfect intent, and without perfect intent it's impossible to hit the exact point on the edge of the building. If the target point is even a nanometer offset from the edge, then the template can't go downwards because the roof blocks it.

 

touching the exact edge is super easy to do. any 2 solid object in contact are always touching the exact surface of each other (never a point above or below the surface). Take a small template and touch it to a mine's base. The base is touching exactly the edge of your template. Without any more difficulty, you can also make the template touch the exact edge of the base. Take a mine template and angle it on a building edge, points it touches are exactly on the edge, not above or below it.

Take a pen and tap repetitively the edge of your table to make some noise, as long as the pen is angled and not pointing toward the table, every hit it does is on the exact edge of the table. If the pen would be hitting further away than the edge (as you claim it does when saying "it's impossible to hit the exact edge"), that would mean that some part of the pen must actually be inside the table, now then how would that be possible ?

The hard part, would be trying to touch a point not exactly on the edge, such as a point at an exact measurement away from the edge.